In the production of chip board panels, fiber board panels, OSB panels (oriented strand or structural board), LSL panels (laminated strand lumber) and other wood material panels, dosing hoppers are arranged ahead or upstream of the actual spreading elements. These dosing hoppers make it possible to even out a time variation of the volume of the chip, fiber or strand material flow. Simultaneously, they are to make possible a continuous supply of material to the spreading heads. For this purpose, especially a uniform distribution of the chips, fibers and strands (strands) over the entire width of the spreading heads is carried out already in the dosing hopper, and thereby a continuous material flow is delivered to the spreading heads.
In actual practice, both vertical as well as horizontal dosing hoppers are known. The vertical dosing hoppers have mostly been arranged vertically above the entire spreading width of the spreading heads, and have been filled up to a prescribed filling height with glued wood chips in a continuous or discontinuous manner. Such vertical dosing hoppers are very simply embodied, whereby the chips are moved from the top toward the bottom only by their gravity without mechanical conveying elements. Discharge rolls are arranged on the hopper floor and convey the chips to the spreading elements. The vertical hoppers have lost significance in recent years, because different densities are formed on the hopper floor depending on the fill height. This has the disadvantage, that differing discharge quantities to the spreading heads result depending on the material density on the hopper floor.
For this reason, in recent years, horizontal dosing hoppers have preferably been utilized before the spreading elements, with which a substantially constant discharge density results in the discharge of wood chips. Such a horizontal dosing hopper is known from the technical reference book by Deppe/Ernst “Taschenbuch der Spanplattentechnik” (Pocketbook of Chip Panel Technology), 3rd Edition 1991, page 255. In this context, the horizontal dosing hopper is arranged above a spreading head and is supplied or loaded with wood chips from above. For this purpose, a horizontal oscillating conveyor is arranged over the supply housing, and continuously distributes the chips over the entire spreading width. Furthermore, a reverse or return combing apparatus is additionally provided in the horizontal dosing hopper, and serves for a uniform filling height over the entire hopper width, in that the higher-lying wood chip piles are continuously combed backward contrary to the discharge direction. A floor belt is additionally arranged at the hopper floor, and conveys the uniformly high chip layer in the hopper to a discharge opening over the spreading head. Thereby, the chip layer is conveyed against rotating discharge rolls, which mill or till off the layer over the entire filling height and simultaneously convey it into a discharge opening to the spreading head, in order to be spread onto a forming belt.
If long flat wood strands (strands) for producing oriented wood chip panels (OSB or LSL) are to be intermediately stored and distributed over the width in such a horizontal dosing hopper, then intermingled and tangled balled-up snarls will be formed in the horizontal hopper, especially due to the continuous reverse or return combing of the elongated wood strands. Since, besides these tangled areas, layers in which the wood strands lie loosely on top of one another are also present in the hopper, a differing or varying layering pattern arises in the hopper. These differing or varying layering patterns or material areas, however, also comprise very different or varying discharge characteristics, which leads to a non-uniform spreading head loading, and can disadvantageously influence a uniform spreading onto the forming belt.